


The Little Scientist

by hinnuh



Category: Undertale (Video Game)
Genre: Cute, F/M, Gender-Neutral Pronouns, Ghost Penis, PWP, Science
Language: English
Status: Completed
Published: 2016-04-17
Updated: 2016-04-17
Packaged: 2018-06-02 18:34:31
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,254
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/6577831
Author URL: https://archiveofourown.org/users/hinnuh/pseuds/hinnuh
Summary: <blockquote class="userstuff">
              <p>You, the fallen human, have stumbled into a quite well-hidden laboratory and have chosen to investigate. When you find out that it belongs to Sans you agree to take part in some experiments that just so happen to include your body.</p>
            </blockquote>





	The Little Scientist

The day started off very nice, you’ve accomplished quite a bit by helping your friends around town and now you’ve become quite tired. “Time to go home,” you thought to yourself as you exited a house in Snowdin. However, as soon as your foot hit the snow you realized how bad the snowstorm really was. Covering your face you tried your best to run back to the Skeleton brother’s house semi-blinded by the snow and the wind. Several minutes have passed and you finally feel like you’ve gotten pretty close to their home when you tripped over what you could only describe as several old trash cans. “Why,” you said to yourself as you slowly stood up, brushing snow off of your sweater and face. As soon as you managed to wipe yourself off to be basically clean you noticed a door in front of you, hidden behind the trash cans and basically everything else for that matter. The door might as well have been completely invisible except for right now. Letting your curiosity get the best of you has been an issue with you since the start and you weren’t about to let that change now. So, being the curious person that you are, you pushed the door open ever so gently and made your way inside. 

You quietly closed the door behind you, making sure not to make too much noise just incase you weren’t really supposed to be in here. After going through a small hallway you entered the main room of this area that seemed to be located underneath the home of Sans and Papyrus. You considered leaving, knowing quite well how much those two enjoy their utmost privacy but it all came back to your curiosity. You peeked around the corner and noticed that there was a rather often-used couch and dining table in the corner but the rest of the room seemed to be entirely made up of beakers, strange tools and other things you’d find in a scientist's’ laboratory as well a familiar voice. 

“hmm no not that one.” you immediately recognized it as the shorter skeleton brother. Without much thought you walked up to him and peeked over his shoulder, “Wow, that looks crazy neat.” Your words spooked him, causing him to stumble, lose focus, and drop a beaker and some test tubes onto the ground, shattering into several pieces. “what are you doing here? how did you find this place?” Giving him a sweet little smile you gave him your honest answer, “I was blinded by the snow and basically just stumbled upon the door.” Sans looked rather confused as he’s put a lot of effort into hiding his lab from everyone. “hmm. if you can manage to just stumble onto this place then maybe there’s something to the human determination factor after all.” Sans said, scratching his head and turning away from you before walking over to a desk of which he pulled several folders of papers out of. “What do you mean? I’m special because I accidentally found a door?” Sans put all the papers and folders away except for one red folder. Opening it up he carried over a torn paper with red stains on it and looked up at you and down back at it for several moments. “no i believe that the human race has an innate power to find hidden things for the sole purpose of ‘completing’ their life. It sort of functions as if the human’s lifespan is based on a percentage of perfection and completionism. come with me” spoke the skeleton as he grabbed your hand and took you over to the couch. “Sit.” spoke Sans as he kept reading the paper. “This paper i have in my hand is a crude drawing of the human anatomy. Ive never had the pleasure of being this close to one whilst also in a state of work.” you tilted your head in slight confusion. “So you work down here? All the stuff you do outside is just side work for show?” Sans placed the paper on the table beside you and shook his head. “I havent lied to you or anyone else about who i am or what i do. I have several jobs. At first it was so i could have more breaks to stand around and do nothing but when offered this job to work on projects alphys doesnt have time for… well… i didnt realize i had the actual knowledge to do such a thing.” Sans took a step towards you, placing his bony hand on your shoulder. “Look,” said he, “i don’t want you to be scared. But i want to perform some experimentation on the human body. Your human body.” his words send chills down your spine as you look up at him, wide-eyed with flushed cheeks. “Y-You what…?” Sans gently massaged your shoulder. “No need to worry, i’ll be very gentle.” said Sans as he slowly moved his fingers down the length of your arm, stopping at your hand only to wrap his fingers around it, holding it tightly. “Your skin is very soft. But also it’s very smooth. You can really feel the blood inside your veins just by paying close attention to your heartbeat and your pulse. You’re just… full of life.” you blush at his words and squirm around in your seat. “I… I’m full of life? What do you mean?” Sans laughed softly and leaned over, looking you closely in the eyes. “Did you forget? Im a skeleton. The concept of being a living creature is, in itself, absolutely fascinating to me.” you blush more and nibble your lower lip. “Actually, we could be here for quite a long while if i was paying attention to the things i dont understand about you. What i instead want to learn about your body is what similarities it has with mine. Such as… sensitive spots.” your eyes somehow got bigger as you let out a gentle gasp, “S-Sensitive? Like w-what…?” somewhat afraid of his intentions you tensed up and took a deep breath. Sans was already moving his hand off of your hand and down onto your waist, investigating your pants. “Skeletons were designed after the human body, this i know. But what i dont know for certain is if they have the same general pleasure points.” 

You could feel yourself beginning to get weaker from the sheer surprise that he’s brought upon you. Using both hands Sans took a decent grip on the waist of your pants, pulling them off of you and gently placing them on the table beside you. “Your legs have a …. Wonderful shape about them.” your breathing sped up as you looked up at him. “I’m ever so curious what exactly gives humans pleasure.” he brings his hands back up to the same place they were before, only this time he’s running his cold, bony fingers along your panties and the areas near them. Very carefully he slips your panties off the same way he did with your pants, placing them on top. Staring intently at your exposed vagina he reaches forward and rubs his thumb against your clit. “Astounding. It’s somehow even softer down here.” you’ve already begun to peep softly, unable to hide your pleasure. “What’s wrong? Does that feel good? Do you want more?” Sans asked, spreading your legs apart and standing up in front of you. “This is very different from my situation. Perhaps the female gender is different from the male.” sans said, staring down at your exposed place. “W-Well what do you have in your pants?” you asked, closing your eyes tightly as you realize how silly your question probably sounded. “Well, i guess i should show you since i’m doing a comparison.” with that, sans undid his pants and reached inside, pulling out a rather hard glowing blue penis. Despite looking as if it were a ghost penis it looked rather tantalizing. It was long, thick, and even had the veins that made it look strong. You stared intently at it and gasped. “Don’t worry, i know how to use it, i wont hurt you.” it didnt occur to sans at first but he realized that, in order to truly understand the pleasure points this human female body has he needs to pleasure it properly and there's only one sure way to do that. 

He leaned over you, placing his hands on your shoulders and forcing you to lean back comfortably. “Just get comfortable, i want you to enjoy this.” spoke sans. You took a deep breath before responding, “g-get comfortable… for what?” you asked, scared. Sans slowly pressed the head of his large dick against the entrance to your vagina. “I want you to enjoy yourself. This doesnt have to feel like work.” you nodded and bit down on your lower lip again, rather terrified. You’ve always wanted sans to have his way with you. You just didnt realize how smart and well-read he was. He was just perfect for you. 

Sans got ahead of himself and pushed his hard dick inside of you. Feeling the pressure caused both of you to make noises, but the noises Sans made were not usual to him. “Wow… i… i didn't realize how easy it was to feel this great…” you gave him a big smile and wrapped your arms around his torso. “It is great… isn’t it?” sans nodded at you and slowly moved his hips back and forth out of sheer reflex and began to let out deep moans. You moaned along with him and could already feel yourself tightening around him. He slid both hands onto your large breasts and gave them a squeeze. “Mmh, they feel so soft in my hands. Your whole body is just… amazing.” his words gave you the chills, making you shiver and breathe even faster. Sans began to grunt and moan more as he thrusted in and out of you, feeling his whole length become moist from your wetness. You wrapped your legs around him as well, not wanting him to ever stop being so close to you. You looked you in the eye and you looked back at him. Although mostly just bones, you could swear that you could feel his heart beating. His thrusting became faster and more controlled as he held you tightly, admiring every inch of your body. “Nnngh, i can feel a heavy pressure… i wonder if this is natural for me…” sans said, somewhat concerned. You nodded and gave him a big smile before kissing his teeth sweetly. “You’re… enjoying it. Just keep going.” your words assured him, giving him the courage to follow through. He started to go even faster, letting the pressure drive him. “Oh my god… i dont know if i can manage to do this any longer…” said sans, feeling his dick throb inside of your extremely wet pussy. You smiled even bigger than before and could feel your hole tightening it’s grip on his length. “Just let it go… y-you’ll know when it’s time…” you knew he was getting close to climax and it was making you all that more excited. You’ve been down here for quite a while and have dreamed of him making love to you, telling you he loves you and cumming deep inside of you. Maybe now it could be a reality. You on the other hand were out of time already and had already begun cumming for the first time. Your face scrunched up and you moaned loudly. Your pussy repeatedly tightened around his dick before going back to it’s original tightness, causing you to sigh of happiness. Sans looked down and noticed some what stuff near the base of his dick where he would normally stop and pull out of you. “What is this…?” sans asked. “I-its…” you said, embarrassed, “i came… you made me feel so good.” your words were completely sincere and they made you feel so good about the whole situation. “Is this what the pressure is? Will i do this too?” asked sans as he then moaned louder and kept pounding into you, faster and faster each time. “Yes!” you said loudly, “god yes! Keep going and you’ll cum too!” sans grabbed your breasts tightly, fucking your wet hole even harder. “Please, Sans! Cum for me! Cum inside of me!” you nearly screamed your words, proud to be his first time. Sans nodded, thinking he understood the concept finally. He continued to thrust into you, each one harder than the last. The pressure eventually became too much for him and he slid his hands down, tightly gripping your hips as he slowed his speed but increased the power that he thrusted into you. “I...I…” said Sans as he tried to tell you that he was cumming. You happily nodded, knowing what he wanted to say. Before you could beg for him to keep going you could feel him doing it. The sheer amount of cum that poured into you was enough to fill a water glass. Your eyes rolled into the back of your head and it even made you cum again, harder than before. Your body went limp along with his and you let out a sigh of relief. “I..I hope I didn’t say anything wrong.” you said, looking up at Sans. He looked at you and you swear you could feel him smiling. “No. you were--- are perfect. Please consider staying here longer. I need an assistant.”

**Author's Note:**

> I didn't even realize scientist Sans existed until the other day. Like most things I post here I do it because my spousal unit requested I write something for them or something of that sort. I sure hope y'all like the way I put this little diddy together. Lemme know whatcha think.


End file.
